North American Network Operators Group

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The next broadband killer: advanced operating systems?

  • From: Leo Bicknell
  • Date: Sun Oct 21 22:46:48 2007

Windows Vista, and next week Mac OS X Leopard introduced a significant
improvement to the TCP stack, Window Auto-Tuning.  FreeBSD is
committing TCP Socket Buffer Auto-Sizing in FreeBSD 7.  I've also
been told similar features are in the 2.6 Kernel used by several
popular Linux distributions.

Today a large number of consumer / web server combinations are limited
to a 32k window size, which on a 60ms link across the country limits
the speed of a single TCP connection to 533kbytes/sec, or 4.2Mbits/sec.
Users with 6 and 8 MBps broadband connections can't even fill their
pipe on a software download.

With these improvements in both clients and servers soon these
systems may auto-tune to fill 100Mbps (or larger) pipes.  Related
to our current discussion of bittorrent clients as much as they are
"unfair" by trying to use the entire pipe, will these auto-tuning
improvements create the same situation?

       Leo Bicknell - [email protected] - CCIE 3440
        PGP keys at
Read TMBG List - [email protected],

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